Syringe-type ejector

ABSTRACT

The syringe dispenser includes a syringe and a plunger. The plunger includes a first shaft member including a piston and second shaft member configured to be fitted in a tubular portion of the first shaft member. The first shaft member includes an elastic piece, the elastic piece being provided with a slide projection configured to slide on an inner surface of the syringe and a lock projection configured to be locked against the syringe. The second shaft member includes a pressing shaft configured to be fitted in the tubular portion. The pressing shaft is provided in a front end thereof with an end surface configured to press a free end of the elastic piece. In response to pressing from the end surface, the lock projection is locked against the rear end of the syringe, and in response to the pressing being released, the locking of the lock projection is released.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to and the benefit of JapanesePatent Application No. 2015-213403 filed on Oct. 29, 2015, the entirecontents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a syringe-type ejector (hereinafter,called a syringe dispenser) including a syringe and a plunger configuredto be pushed into the syringe, and the present disclosure also relatesto a technology for pushing the plunger in a stepwise fashion.

BACKGROUND

Examples of syringe dispensers include those that are configured todispense a content medium such as a medicinal fluid in response to aplunger being pushed into a syringe (refer, for example, to PatentLiterature 1).

However, it has been difficult for such a conventional syringe dispenserin which the plunger is merely pushed into the syringe to divide theamount of the content medium into smaller fractions to be dispensed.

To address the above problem, Patent Literature 2 describes a syringedispenser that is capable of dispensing the content medium in two partsby pushing the plunger in two steps.

CITATION LIST Patent Literatures

-   PTL1: JPH07213612A-   PTL2: JP2013208603A

SUMMARY Technical Problem

In the syringe dispenser described in Patent Literature 2, the plungeris configured by two shafts, and there is room for improvement in termsof operability based on cooperation of the shafts.

The present disclosure is to provide a syringe dispenser that isconfigured to divide the amount of the content medium into smallerfractions to be dispensed and that also provides improved operability.

Solution to Problem

To solve the above problem, one of aspects of the present disclosureresides in a syringe dispenser including: a syringe; and a plungerconfigured to be pushed into the syringe. The plunger includes: a firstshaft member including a piston at a front end thereof; and a secondshaft member configured to be fitted in a tubular portion of the firstshaft member. The first shaft member includes at least one elastic pieceextending toward a rear side, the elastic piece being provided with aslide projection and a lock projection, the slide projection beingconfigured to enter through a rear end opening portion of the syringeand slide on an inner circumferential surface of the syringe, and thelock projection being configured to be locked against a rear end of thesyringe. The second shaft member includes a pressing shaft configured tobe fitted in the tubular portion, the pressing shaft being provided in afront end thereof with an end surface configured to press a free end ofthe elastic piece, and the pressing shaft being also provided on anouter circumferential surface thereof with an engagement projectionconfigured to engage with an engagement portion of the tubular portionto prevent the second shaft member from slipping out of the tubularportion. In response to pressing from the end surface, the free end ofthe elastic piece is restrained between the end surface and the syringe,and the elastic piece undergoes a flexure deformation starting from theslide projection, and thus, the lock projection is locked against therear end of the syringe, and in response to the pressing being released,the locking of the lock projection is released due to a restoring forcefrom the flexure deformation that starts from the slide projection.

Preferably, the tubular portion is provided with an opening penetratingin a radial direction, and the elastic piece is arranged within theopening, with a rear end edge of the opening serving as the engagementportion.

Preferably, a position of the end surface when the pressing is releasedis determined by the engagement projection abutting against theengagement portion of the tubular portion.

Preferably, the slide projection and the lock projection are coupled bya thinned portion having a thickness in a radial direction that isreduced.

Preferably, the elastic piece, in a portion from a base portion to theslide projection thereof, is formed to have a thickness in a radialdirection that is gradually increased.

Preferably, the end surface is provided with a tapered surface.

Preferably, the first shaft member is provided on an outercircumferential surface thereof with a rib configured to engage with therear end of the syringe in a position in which the pressing is started.

ADVANTAGEOUS EFFECT

The present disclosure provides a syringe dispenser that is configuredto divide the amount of the content medium into smaller fractions to bedispensed and that also provides improved operability.

BRIEF DESCRIPTION OF THE DRAWING

In the accompanying drawings:

FIG. 1A is a plan view of a syringe dispenser in an initial state beforeoperation according to one of embodiments of the present disclosure;

FIG. 1B is a front partial sectional view of the syringe dispenser inthe initial state before operation according to the one of embodiments;

FIG. 1C is a sectional view along an A-A section of a plunger that isused in the syringe dispenser in the initial state before operationaccording to the one of embodiments;

FIG. 2 is a left-side partial sectional view of the syringe dispenser inthe initial state before operation according to the one of embodiments;

FIG. 3A a plan view of a first shaft member that is used in the syringedispenser according to the one of embodiments;

FIG. 3B is a front half-sectional view of the first shaft member that isused in the syringe dispenser according to the one of embodiments;

FIG. 4A a plan view of a second shaft member that is used in the syringedispenser according to the one of embodiments;

FIG. 4B a front half-sectional view of the second shaft member that isused in the syringe dispenser according to the one of embodiments;

FIG. 5 is a perspective view of the first shaft member and the secondshaft member that constitute the plunger used in the syringe dispenseraccording to the one of embodiments;

FIG. 6A is a front partial sectional view illustrating a state where afirst dispensing by the syringe dispenser according to the one ofembodiments is completed;

FIG. 6B is an enlarged view of a flange portion illustrated in FIG. 6A;

FIG. 7A is a front partial sectional view illustrating a state wherepreparation for a second dispensing by the syringe dispenser accordingto the one of embodiments is completed; and

FIG. 7B is an enlarged view of the flange portion illustrated in FIG.7A.

DETAILED DESCRIPTION

The following describes a syringe dispenser 1 according to one ofembodiments of the present disclosure in detail with reference to thedrawings.

In FIG. 1B, reference numeral 2 denotes a syringe in which a contentmedium C, such as a medicine, may be filled. Note that in thespecification, claims, abstract, and drawings, the direction (i.e.,downward direction in FIG. 1B) in which the content medium C isdispensed is defined as a front side, and the side (i.e., upwarddirection in FIG. 1B) in which a second shaft portion 3 b is located isdefined as a rear side. The syringe 2 includes a hollow trunk 2 a and afront end portion 2 c, which is integrally connected to the trunk 2 avia a shoulder 2 b. The front end portion 2 c has a diameter that issmaller than that of the trunk 2 a. The syringe 2 also includes, at arear end of the trunk 2 a, a syringe's rear end portion 2 d ₀, whosediameter is increased, and a flange portion 2 d, which is fitted to thesyringe's rear end portion 2 d ₀. That is to say, the flange portion 2 dconstitutes the rear end of the syringe 2.

Reference numeral 3 refers to a plunger configured to be accommodated inthe syringe 2. The plunger 3 includes a first shaft member 3 a and thesecond shaft member 3 b, which is arranged at the rear of the firstshaft member 3 a.

The first shaft member 3 a includes a piston 4 at a front end portion ofthe first shaft member 3 a that is configured to be accommodated in thesyringe 2. The piston 4 is made of an elastic material, such as rubber,and is slidably held on an inner circumferential surface 2 f of thesyringe trunk 2 a.

Between the syringe 2 and the piston 4, space R is defined. The space Ris configured to be filled with the content medium C. The content mediumC filled in the space R is pressure-fed to a front end through hole A₁,which is provided in the front end portion 2 c, in response to theplunger 3 being pushed in.

As illustrated in FIG. 5, the first shaft member 3 a includes a tubularportion 3 a ₉, which is disposed on the rear side of the first shaftmember 3 a. The tubular portion 3 a ₉ has a circumferential wallprovided with an opening 3 a ₈, which penetrates in the radialdirection. The opening 3 a ₈ communicates with a tubular portion'sinsertion hole 3 a ₁₀, into which the second shaft 3 b is to beinserted.

As illustrated in FIG. 1B, the first shaft member 3 a is providedintegrally with two elastic pieces 3 a ₁, which extend toward the rearside. Each elastic piece 3 a ₁ is provided with a slide projection 3 a ₂and a lock projection 3 a ₃. The slide projection 3 a ₂ and the lockprojection 3 a ₃ are disposed at an interval along an axis line O towardthe rear side in the order of the slide projection 3 a ₂ and the lockprojection 3 a ₃. The slide projection 3 a ₂ has a tapered portion 3 f₀, which tapers toward a front end thereof. With the aboveconfiguration, the slide projection 3 a ₂ may enter through a rear endopening portion A₂ of the syringe 2 and slide on the innercircumferential surface 2 f of the syringe 2, and accordingly, permitthe plunger 3 to be pushed in. Furthermore, the slide projection 3 a ₂and the lock projection 3 a ₃ are coupled by a thinned portion 3 a ₆ sothat the elastic piece 3 a ₁ may easily undergo a flexure deformationstarting from the slide projection 3 a ₂. As described later, the lockprojection 3 a ₃ is configured to be caught against an innercircumferential end of the flange portion 2 d, which is disposed at therear end of the syringe 2, to prevent the plunger 3 from being pushed infurther. As illustrated in FIG. 5, the elastic piece 3 a ₁ is arrangedto be accommodated within the opening 3 a ₈. As illustrated in FIG. 1B,an outer diameter of the slide projection 3 a ₂ in an initial state(initial position) is larger than an inner diameter of the syringe 2.

As illustrated for example in FIGS. 1B and 5, the first shaft member 3 aincludes a base portion 3 a ₄, to which the piston 4 is fixed, and theelastic pieces 3 a ₁ are coupled to a rear end of the base portion 3 a₄. The base portion 3 a ₄ may adopt, for example, a shape as illustratedin FIG. 5 in which two wall surfaces extending in the front-reardirection (i.e., vertical direction in FIG. 5) to form a cross-shapedsectional shape are arranged between a disc-shaped front wall and adisc-shaped rear wall in a manner such that the two wall surfaces crosseach other at right angles. The above configuration allows each elasticpiece 3 a ₁, on the free end side thereof that is provided with the lockprojection 3 a ₃, to undergo flexure deformation in a manner such thatthe elastic piece 3 a ₁ may be deformed and restored, with a portion ofthe elastic piece 3 a ₁ coupled to the base portion 3 a ₄ serving as afixed end. The hollow cylindrical-shaped tubular portion 3 a ₉ is alsocoupled to the rear end of the base portion 3 a ₄.

The lock projection 3 a ₃ is formed on the free end side of the elasticpiece 3 a ₁ in an integrated manner. As illustrated in FIGS. 3B and 5, arear end surface of the lock projection 3 a ₃ is formed as a pressedsurface 3 a ₇, which is configured to receive pressing force from thesecond shaft member 3 b. As illustrated in FIG. 3B, the pressed surface3 a ₇ is configured by a pressed flat surface 3 a ₇₀, which extends inthe horizontal direction at an inner end of the pressed surface 3 a ₇ inthe radial direction, and a pressed tapered surface 3 a ₇₁, which isdisposed on the outer circumferential side of the pressed flat surface 3a ₇₀. The pressed tapered surface 3 a ₇₁ has a tapered surface thatslightly tapers toward the front side in the outer circumferentialdirection. As described later, the pressed flat surface 3 a ₇₀ serves asa surface configured to receive pressing force from the second shaftmember 3 b in a first dispensing of the content medium C. The pressedtapered surface 3 a ₇₁ serves as a surface configured to receivepressing force from the second shaft member 3 b in a second dispensingof the content medium C.

As illustrated for example in FIGS. 2 and 5, the tubular portion 3 a ₉is provided, on an outer surface thereof, with ribs 3 a ₁₂ disposed intwo positions along the front-rear direction (i.e., two positions alongthe vertical direction in FIG. 2). The rib 3 a ₁₂ on the front side isdisposed so that this rib 3 a ₁₂ engages with the inner circumferentialend of the flange portion 2 d in a position of the plunger 3 in whichthe first dispensing of the content medium C is started. Similarly, therib 3 a ₁₂ on the rear side is disposed so that this rib 3 a ₁₂ engageswith the inner circumferential end of the flange portion 2 d in aposition of the plunger 3 in which the second dispensing of the contentmedium C is started. The above configuration allows a user of thesyringe dispenser 1 to orient the front end through hole A_(l) toward anobject of dispensing in the positions in which the ribs 3 a ₁₂ engagewith the inner circumferential end of the flange portion 2 d. The ribs 3a ₁₂ are also configured to climb over the inner circumferential end ofthe flange portion 2 d by the user pressing the plunger 3, and thisensures that the content medium C may be dispensed to the object.Additionally, a certain level of pressing force is necessary for theribs 3 a ₁₂ to climb over the inner circumferential end of the flangeportion 2 d. Accordingly, the user is to push in the plunger 3 withelevated pressing force, and the content medium C is dispensed withgreat force. This is especially preferable when the content medium C isdispensed (sprayed) in the form of spray.

FIGS. 4A and 4B are a plan view and a front half-sectional view of thesecond shaft member 3 b. As illustrated in FIG. 4B, the second shaftmember 3 b is configured by a pressing shaft 3 b ₄ and a pressing flange3 b ₁, which is disposed on the rear side of (i.e., above in FIG. 4B)the pressing shaft 3 b ₄ and which is used by the user to push in theplunger 3. As illustrated in FIG. 4B, the pressing shaft 3 b ₄ has abottomed tubular shape with a front end surface 3 f ₃ formed as a flatsurface that is orthogonal to the axis line O. Additionally, thepressing shaft 3 b ₄ may have other shapes, such as a hollow tubularshape, a topped tubular shape, and a solid tubular shape, than thebottomed tubular shape. Furthermore, the pressing flange 3 b ₁ may beomitted. As illustrated in FIG. 4A, the pressing shaft 3 b ₄ isprovided, on an outer surface thereof, with large-diameter portions 3 b₃ disposed in opposing positions on the circumference. At a front end(i.e., lower end in FIG. 4B) of each large-diameter portion 3 b ₃, apressing end surface 3 f ₁, which is configured to abut against thepressed surface 3 a ₇ of the first shaft member 3 a to transmit pressingforce, is provided. On an outer surface of the large-diameter portion 3b ₃, an engagement projection 3 b ₂ is further provided. The engagementprojection 3 b ₂ is configured to engage with the opening 3 a ₈, whichis provided in the tubular portion 3 a ₉, to prevent the second shaftmember 3 b from slipping out of the tubular portion 3 a ₉ when thesecond shaft member 3 b is inserted into the tubular portion's insertionhole 3 a _(1o) of the first shaft member 3 a. Additionally, the way toengage the engagement projection 3 b ₂ is not limited to the above mode.For example, a projection may be provided on an inner circumferentialsurface of the tubular portion 3 a ₉, and the engagement projection 3 b₂ may be configured to climb over the projection. As illustrated forexample in FIG. 5, the tubular portion's insertion hole 3 a ₁₀ of thefirst shaft member 3 a is provided with large-diameter grooves 3 a ₁₃.When the second shaft member 3 b is inserted into the tubular portion'sinsertion hole 3 a ₁₀, the large-diameter portions 3 b ₃ are engaged inthe large-diameter grooves 3 a ₁₃ of the first shaft member 3 a. Theabove configuration improves the ease of assembly by allowing alignmentin the circumferential direction to be performed at the same time asinserting the second shaft member 3 b into the first shaft member 3 a.Additionally, the large-diameter portions 3 b ₃ and the large-diametergrooves 3 a ₁₃ are not indispensable configurations, and the tubularportion's insertion hole 3 a ₁₀ and the pressing shaft 3 b ₄ may havecylindrical-shaped side surfaces. On the inner circumferential side ofthe pressing end surface 3 f ₁, a tapered surface 3 f ₂ is disposed overthe entire circumference.

Next, how to use the present embodiment is described with reference toan example where a nasal drop is used as the content medium C.

Firstly, the user inserts the front end portion 2 c into one of thenostrils in the state where the front rib 3 a ₁₂ is in abutment againstthe inner circumferential end of the flange portion 2 d as illustratedin FIG. 2. Subsequently, the user pushes in the pressing flange 3 b ₁ ofthe second shaft member 3 b toward the front side. At this time, sincethe pressing shaft 3 b ₄ of the second shaft member 3 b is inserted intothe tubular portion 3 a ₉ of the first shaft member 3 a, reliablepressing operation is achieved without causing the second shaft member 3b to stagger or tilt with respect to the first shaft member 3 a when thesecond shaft member 3 b is pressed. Then, as illustrated in FIG. 6B,each pressing end surface 3 f ₁, which is provided in the second shaftmember 3 b, abuts against the pressed surface 3 a ₇, which is disposedon the rear end surface of the corresponding lock projection 3 a ₃ ofthe first shaft member 3 a. At this time, the pressing end surface 3 f ₁abuts against the pressed flat surface 3 a ₇₀ of the pressed surface 3 a₇ that is disposed on the inner circumferential side. Consequently, thefirst shaft member 3 a, together with the second shaft member 3 b, ispushed in toward the front side. At this time, since the slideprojection 3 a ₂ of the first shaft member 3 a has the tapered portion 3f ₀, which tapers toward the front end, the first shaft member 3 aenters the syringe 2 through the syringe's rear end opening portion A₂.

Since the pressing end surface 3 f ₁ of the second shaft member 3 bcontacts and presses the pressed flat surface 3 a ₇₀ of each elasticpiece 3 a ₁, the movement of the free end of the elastic piece 3 a ₁ isrestrained between the pressing end surface 3 f ₁ and the syringe 2. Asa result, as illustrated in FIG. 6A, the elastic piece 3 a ₁ undergoes aflexure deformation starting from the slide projection 3 a ₂. Herein,the deformation of the pressed surface 3 a ₇ toward the inner side inthe radial direction is regulated by the pressing end surface 3 f ₁ andthe tapered surface 3 f ₂, and accordingly, the lock projection 3 a ₃remains in the initial position on the free end of the elastic piece 3 a₁. Additionally, the outer diameter or the like of the second shaftmember 3 b may also be altered as appropriate to displace the free endtoward the outer circumferential side. By the slide projection 3 a ₂sliding on the inner circumferential surface 2 f of the syringe 2 whileundergoing the aforementioned flexure deformation, the plunger 3 isallowed to be pushed in. The above processes are used to dispense ametered amount of the content medium C (nasal drop) from the front endthrough hole A₁ into the nostril until the lock projection 3 a ₃ of theelastic piece 3 a ₁ comes into contact with the rear end of the flangeportion 2 d as illustrated in FIG. 6B.

Once the lock projection 3 a ₃ of the elastic piece 3 a ₁ comes intocontact with the rear end of the flange portion 2 d, the plunger 3cannot be pushed in anymore. Accordingly, the first dispensing is endedwhile a certain amount of the content medium C (nasal drop) stillremains in the space R. Additionally, the volume of the content medium Cdispensed for the first time may be determined as appropriate inaccordance with intended use. For example, the volume of the contentmedium C dispensed for the first time may be half the volume of thespace R illustrated in FIG. 1B.

Subsequently, when the pressing of the second shaft member 3 b isreleased, as illustrated in FIG. 7A, the free end side of the elasticpiece 3 a ₁ undergoes restoration starting from the slide projection 3 a₂ due to a restoring force from the aforementioned flexure deformation.At this time, the second shaft member 3 b is pushed back to the rearside by the restoring force of the elastic piece 3 a ₁, and, asillustrated in FIG. 7A, the engagement projection 3 b ₂, which isprovided in the second shaft member 3 b, returns to a rear end of theopening 3 a ₈ of the first shaft member 3 a. Furthermore, since thefixed end side of the elastic piece 3 a ₁ remains deformed to bedisplaced toward the inner circumferential side as it extends toward therear side, the free end side of the elastic piece 3 a ₁ is restoredtoward the inner circumferential direction so that the free end side isaligned with the fixed end side as illustrated in FIG. 7A.

Accordingly, the lock projection 3 a ₃ also follows the free end side ofthe elastic piece 3 a ₁ and is deformed toward the inner circumferentialdirection, and as illustrated in FIG. 7A, the locked state of the lockprojection 3 a ₃ is released. Additionally, since the engagementprojection 3 b ₂ serves to prevent the second shaft member 3 b fromslipping out, once the engagement projection 3 b ₂ comes into abutmentagainst the rear end of the opening 3 a ₈, the second shaft member 3 bwill not be displaced to the rear side any further.

Especially in the present embodiment, as illustrated in FIG. 7B, sincethe tapered surface 3 f ₂ is disposed on the inner circumferential sideof the pressing end surface 3 f ₁, the second shaft member 3 b is pushedback to the rear side due to the aforementioned restoring force when thepressing of the second shaft member 3 b is released, and the lockprojection 3 a ₃ previously in abutment against the pressing end surface3 f ₁ may be displaced toward the inner circumferential direction alongthe tapered surface 3 f ₂. Additionally, although in the presentembodiment the second shaft member 3 b is configured to be pushed backto the rear side due to the restoring force of the elastic piece 3 a ₁when the pressing is released, the present disclosure is not limited tothis embodiment, and the second shaft member 3 b may also be configuredto be pulled back to the rear side in response to the user pulling thesecond shaft member 3 b. Furthermore, since the slide projection 3 a ₂and the lock projection 3 a ₃ are coupled by the thinned portion 3 a ₆,the lock projection 3 a ₃ is configured to be displaced toward the innercircumferential side more significantly when the pressing of the secondshaft member 3 b is released. Moreover, as illustrated in the enlargedview of FIG. 7B, the pressed tapered surface 3 a ₇₁ is provided on thepressed surface 3 a ₇ on the free end of the elastic piece 3 a ₁, andthe pressed tapered surface 3 a ₇₁ slightly tapers toward the front sidein the outer circumferential direction. With the above configuration, asillustrated in FIG. 7B, even when the lock projection 3 a ₃ of theelastic piece 3 a ₁ is displaced toward the inner circumferentialdirection due to the flexure deformation starting from the slideprojection 3 a ₂, the deformation of the free end of the elastic piece 3a ₁ in the radial direction is not interfered with by the second shaftmember 3 b. Thus, the deformation of the lock projection 3 a ₃ towardthe inner circumferential direction is not interfered with by the secondshaft member 3 b.

In this way, in the present embodiment, the lock projection 3 a ₃ isconfigured to be displaced to a great extent toward the innercircumferential direction when the pressing of the second shaft member 3b is released. The above configuration allows a large overlap allowancer between the lock projection 3 a ₃ and the rear end of the flangeportion 2 d that helps stop the first dispensing of the content medium C(refer to FIG. 6B). Accordingly, the first dispensing of the contentmedium C may be stopped reliably.

After the pressing of the second shaft member 3 b is released, thesecond dispensing may be achieved by pressing the second shaft member 3b again in the state where the rear rib 3 a ₁₂ is in abutment againstthe inner circumferential end of the flange portion 2 d as illustratedin FIG. 7A. That is to say, in the present embodiment, by pressing thesecond shaft member 3 b again after releasing the pressing of the secondshaft member 3 b, as illustrated in FIG. 7B, the resulting restorationof the elastic piece 3 a ₁ that starts from the slide projection 3 a ₂brings the front end surface 3 f ₃ of the second shaft member 3 b intocontact with the pressed tapered surface 3 a ₇₁. For the above reason,the first shaft member 3 a may be pushed in by pressing the second shaftmember 3 b again.

Especially in the present embodiment, the pressed tapered surface 3 a ₇₁is tapered toward the front side as it extends to the outercircumferential direction in the initial state. Accordingly, when thefree end side of the elastic piece 3 a ₁ undergoes the restorationstarting from the slide projection 3 a ₂, the front end surface 3 f ₃ ofthe second shaft member 3 b and the pressed tapered surface 3 a ₇₁contact in substantially a parallel state to each other. The aboveconfiguration allows the first shaft member 3 a to be pushed insmoothly.

As illustrated in FIG. 7A, after releasing the pressing of the secondshaft member 3 b to push back the second shaft member 3 b, the userinserts the front end portion 2 c into the other nostril. The user maydispense the content medium (nasal drop) remaining in the space R to thenostril through the front end through hole A₁ simply by pushing in thesecond shaft member 3 b again.

Additionally, it is preferable to adjust the heights of the front andrear ribs 3 a ₁₂ so that the pressing force necessary for one rib 3 a ₁₂to pass through the inner circumferential end of the flange portion 2 dat the first dispensing of the content medium C substantially equals thepressing force necessary for the other rib 3 a ₁₂ to pass through theinner circumferential end of the flange portion 2 d at the seconddispensing of the content medium C.

As described above, according to the present embodiment, the amount ofthe content medium C may be divided into smaller fractions to bedispensed. Furthermore, since in the present embodiment the seconddispensing is achieved by pressing the second shaft member 3 b againafter releasing the pressing of the second shaft member 3 b, there is noneed to pass the syringe dispenser 1 from one hand to the other for thesecond dispensing. Thus, the user is able to divide the amount of thecontent medium C into smaller fractions by one-hand operation.Especially in the present embodiment, the plunger 3 is configured by thefirst shaft member 3 a, which includes the piston 4 in the front end,and the second shaft member 3 b, which includes the bottomedtubular-shaped pressing shaft 3 b ₄ configured to be fitted in thetubular portion 3 a ₉ of the first shaft member 3 a. Furthermore, theengagement projection 3 b ₂, which is provided on the outercircumferential surface of the second shaft member 3 b, is configured toengage with the opening 3 a ₈ of the tubular portion 3 a ₉. The aboveconfigurations allow the second shaft member 3 b to be displacedsmoothly in the axis O direction within the tubular portion's insertionhole 3 a ₁₀ in response to pressing and to the pressing being released.Furthermore, with the engagement projection 3 b ₂ being engaged, thesecond shaft member 3 b is prevented from slipping out of the firstshaft member 3 a. That is to say, the second shaft member 3 b does notstagger or tilt with respect to the first shaft member 3 a when thesecond shaft member 3 b is pressed. Accordingly, operability of thesyringe dispenser 1 at the time of pressing is improved.

Moreover, according to the present embodiment, the position of the frontend surface 3 f ₃ when the pressing of the second shaft member 3 b isreleased is determined by the engagement projection 3 b ₂ abuttingagainst the opening 3 a ₈ of the tubular portion 3 a ₉. For the abovereason, when the pressing of the second shaft member 3 b is released,the resulting push-back does not excessively separate the front endsurface 3 f ₃ of the second shaft member 3 b from the pressed surface 3a ₇. Accordingly, the second dispensing of the content medium C isachieved smoothly.

Moreover, according to the present embodiment, the slide projection 3 a₂ and the lock projection 3 a ₃ are coupled by the thinned portion 3 a₆, which has a thickness in the radial direction that is reduced.Moreover, since in the present embodiment the pressing shaft 3 b ₄ ofthe second shaft member 3 b has the bottomed tubular shape with thefront end surface 3 f ₃ formed as the flat surface, the free end of eachelastic piece 3 a ₁, when being displaced in the inner circumferentialdirection, does not contact the second shaft member 3 b from the radialdirection. Thus, the lock projection 3 a ₃ is configured to be displacedto a great extent toward the inner circumferential direction due to therestoring force when the pressing is released. The above configurationallows the large overlap allowance r between the lock projection 3 a ₃and the rear end of the flange portion 2 d that helps stop the firstdispensing of the content medium C (refer to FIG. 6B). Accordingly, thefirst dispensing of the content medium C may be stopped reliably.

Moreover, according to the present embodiment, with the tapered portion3 f ₀ disposed from a base portion to the slide projection 3 a ₂, theelastic piece 3 a ₁ is formed to have a thickness in the radialdirection that is gradually increased. Due to the above configuration,the first shaft member 3 a may be pushed in smoothly until the slideprojection 3 a ₂ slides on the inner circumferential surface 2 f of thesyringe 2 after the second shaft member 3 b starts to be pressed.

Moreover, according to the present embodiment, the tapered surface 3 f ₂is disposed on the inner circumferential side of the pressing endsurface 3 f ₁. The above configuration allows the lock projection 3 a ₃to be displaced toward the inner circumferential direction along thetapered surface 3 f ₂ easily when the pressing with the pressing endsurface 3 f ₁ is released.

Moreover, according to the present embodiment, the ribs 3 a ₁₂, each ofwhich is configured to engage with the inner circumferential end of theflange portion 2 d in the corresponding position in which the pressingis started, are disposed on the outer circumferential surface of thefirst shaft member 3 a. The above configuration allows the user to graspthe positions of the plunger 3 in which the dispensing of the contentmedium C is started based on resistance against the pressing.Accordingly, the user will not dispense the content medium C by pushingin the plunger 3 erroneously in an unintended position.

Moreover, according to the present embodiment, since the tubular-shapedsecond shaft member 3 b is configured to be inserted into the tubularportion's insertion hole 3 a ₁₀ of the first shaft member 3 a, theplunger 3 is easy to assemble. Besides, the large-diameter groove 3 a ₁₃is provided in the tubular portion's insertion hole 3 a ₁₀, and thelarge-diameter portion 3 b ₃ is configured to be engaged in thelarge-diameter groove 3 a ₁₃ of the first shaft member 3 a when thesecond shaft member 3 b is inserted into the tubular portion's insertionhole 3 a ₁₀. The above configuration further improves the ease ofassembly by allowing alignment in the circumferential direction to beperformed at the same time as inserting the second shaft member 3 b intothe first shaft member 3 a.

Although various modes of the embodiment of the present disclosure havebeen described above, a variety of modifications are possible accordingto the present disclosure. For example, although the elastic piece 3 a ₁may be disposed in at least a single position, the elastic piece 3 a ₁is preferably disposed in plurality as in the present embodiment toreliably stop the plunger 3 and to accurately divide the amount of thecontent medium C into smaller fractions. Especially, arranging the pairof elastic pieces 3 a ₁ in opposing positions as in the presentembodiment allows favorable operation since stable balance is achievedaround the axis line 0. Although in the above embodiment the contentmedium C is described to be dispensed as a normal fluid, the contentmedium C may be dispensed in various manners such as in the form of foamor spray according to the present disclosure.

INDUSTRIAL APPLICABILITY

The present disclosure may be adopted in the syringe dispenser 1 withany of a variety of configurations which include the syringe 2 and theplunger 3 configured to be pushed into the syringe 2. The content mediumC is not limited to the nasal drop, and a variety of content media C maybe adopted.

REFERENCE SIGNS LIST

1 Syringe dispenser

2 Syringe

2 a Trunk

2 b Shoulder

2 c Front end portion

2 d Flange portion

2 d ₀ Syringe's rear end portion

2 f Inner circumferential surface

3 Plunger

3 a First shaft member

3 a ₁ Elastic piece

3 a ₂ Slide projection

3 a ₃ Lock projection

3 a ₄ Base portion

3 a ₆ Thinned portion

3 a ₇ Pressed surface

3 a ₇₀ Pressed flat surface

3 a ₇₁ Pressed tapered surface

3 a ₈ Opening

3 a ₉ Tubular portion

3 a ₁₀ Tubular portion's insertion hole

3 a ₁₁ Piston fixing male screw

3 a ₁₂ Rib

3 a ₁₃ Large-diameter groove

3 b Second shaft member

3 b ₁ Pressing flange

3 b ₂ Engagement projection

3 b ₃ Large-diameter portion

3 b ₄ Pressing shaft

3 f ₀ Tapered portion

3 f ₁ Pressing end surface (end surface)

3 f ₂ Tapered surface

3 f ₃ Front end surface

4 Piston

A₁ Front end through hole

A₂ Rear end opening portion

C Content medium

O Axis line

R Space

r Overlap allowance

1. A syringe dispenser comprising: a syringe; and a plunger configuredto be pushed into the syringe, wherein the plunger includes: a firstshaft member including a piston at a front end thereof; and a secondshaft member configured to be fitted in a tubular portion of the firstshaft member, the first shaft member including at least one elasticpiece extending toward a rear side, the elastic piece being providedwith a slide projection and a lock projection, the slide projectionbeing configured to enter through a rear end opening portion of thesyringe and slide on an inner circumferential surface of the syringe,and the lock projection being configured to be locked against a rear endof the syringe, the second shaft member including a pressing shaftconfigured to be fitted in the tubular portion, the pressing shaft beingprovided in a front end thereof with an end surface configured to pressa free end of the elastic piece, and the pressing shaft being alsoprovided on an outer circumferential surface thereof with an engagementprojection configured to engage with an engagement portion of thetubular portion to prevent the second shaft member from slipping out,and wherein in response to pressing from the end surface, the free endof the elastic piece is restrained between the second shaft member andthe syringe, and the elastic piece undergoes a flexure deformationstarting from the slide projection, and thus, the lock projection islocked against the rear end of the syringe, and in response to thepressing being released, the locking of the lock projection is releaseddue to a restoring force from the flexure deformation that starts fromthe slide projection.
 2. The syringe dispenser of claim 1, wherein thetubular portion is provided with an opening penetrating in a radialdirection, and the elastic piece is arranged within the opening, with arear end edge of the opening serving as the engagement portion.
 3. Thesyringe dispenser of claim 1, wherein a position of the end surface whenthe pressing is released is determined by the engagement projectionabutting against the engagement portion of the tubular portion.
 4. Thesyringe dispenser of any one of claims 1 to 3 and 8, wherein the slideprojection and the lock projection are coupled by a thinned portionhaving a thickness in a radial direction that is reduced.
 5. The syringedispenser of any one of claims 1 to 3 and 8, wherein the elastic piece,in a portion from a base portion to the slide projection thereof, isformed to have a thickness in a radial direction that is graduallyincreased.
 6. The syringe dispenser of any one of claims 1 to 3 and 8,wherein the end surface is provided with a tapered surface.
 7. Thesyringe dispenser of any one of claims 1 to 3 and 8, wherein the firstshaft member is provided on an outer circumferential surface thereofwith a rib configured to engage with the rear end of the syringe in aposition in which the pressing is started.
 8. The syringe dispenser ofclaim 2, wherein a position of the end surface when the pressing isreleased is determined by the engagement projection abutting against theengagement portion of the tubular portion.